Selective signaling system



Aug. 11, 1953 E. VROOM 2,648,831

SELECTIVE SIGNALING SYSTEM Filed Aug. 50, 1950 4 Sheets-Sheet 1 ATTORNEY Aug. 11, 1953 E. VROOM SELECTIVE SIGNALING SYSTEM 4 Sheets-Sheet 2 Filed Aug. 30, 1950 II In 9 (V, WW

l/V l ENTOP E. moo/1 ATTOQNEV 4 Sheet-Sheet 5 E. VROOM Aug. 11, 1953 SELECTIVE SIGNALING SYSTEM Filed Aug. 50, 1950 Aug. 11, 1953 E. VROOM ,6

SELECTIVE SIGNALING SYSTEM Filed Aug. 50, 1950 4 Sheets-Sheet 4 EE-r Em J1,

R IT I E .4 H

mifi T l a- E-"I ,I E -I I E' /NVEN 70/? E. VROOM BY ATTORNEY Patented Aug. 11, 1953 UNITED STATEfi RATE NT OFFICE SELECTIVE SIGNALING SYSTEM Application August 30, 1950, SerialNo..182,2,42

6 Claims.

This invention relates to a selective signaling system and more particularly to apparatus operable only in response to the receipt of a representation of the designation of that apparatus.

An object of this invention is the rapid and accurate ascertainment of the receipt of the selected one of a plurality of designations.

The invention may find application in many fields of communication such as in telephone or telegraph switching systems, mobile radio systems, ship-to-shore communication systems, train dispatching systems, etc. Such systems normally comprise a plurality of terminating or. called stations each of which is suitably designated by a number, a series of letters, or a. combination of numbers and letters. In order to establish a communication path to a particular one of such called stations, it is normally necessary for the called party to be informed audibly and/or visually that he is being called. However, in many systems, the signals representing a large group of designations are received by each of the stations. Consequently, it is desirable that means be provided to alert the called party only when his particular designation is received. Therefore, in general, this invention comprises a system operable in response to the receipt of a preselected one only of a plurality of composite signals to energize a visual or audible signal.

A feature of the invention is the utilization of cold cathode gaseous discharge stepping devices each having a plurality of cathodes.

Another feature of the invention is the use of a single multicathode gaseous discharge device for successively counting the pulses representing all of the digits of a designation.

Another feature of the invention is a means for momentarily associating the pulse counting multicathode gaseous discharge device with a register means during the interdigital pauses.

Another feature of the invention is the use of a multicathode gaseous discharge device as a registering means.

The principles of the invention may be more fully understood from the fOllOWll'lg detailed description of preferred embodiments thereof when read with reference to the accompanying drawings in which:

Fig. 1 is an elevational view of a multicathode glow discharge device illustrative of one type of tube suitable for use in the present system;

Fig. 2 is a sectional view taken along of Fig. 1 illustrating the arrangement of the several cathodes and the cooperative relation thereof with the anode, a portion of the anode, being broken away to. show certain of, the cathodes more clearly;

Fig. 3 is. a circuit diagram representing one preferred embodiment of the invention; and

Figs. 4 and 5, when the latter is placedcontiguous to, andto, the right of the iormer, show another preferred embodiment of the invention.

The multicathode stepping tubes which are employed in the present system may be, of any suitable type, A tube operable in.a suitable man-. ner is disclosed, for example, in United; States Patent 2,575,370 granted November 20, 1951, to W. A. Townsend, the disclosure of which is in..- corporated herein by reference. A representation of that tube, is presented as Figs. 1 and 2 of the present disclosure.

In general, the disclosed gaseous discharge device comprises an anode and a plurality of cold cathodes in cooperative. relationship with the anode, the cathodes being, mounted in a row which may be rectilinear, circular or of other geometrical form. The cathodes, or certain of them, are electrically grouped and are so constructed and arranged that the discharge between one cathode and the anode may he steppedor shifted selectively to ajpath between the anode and another cathode in response to signal pulses, the discharge shifting or advancing one position for each pulse.

Referring now to Figs. 1 and 2 of the drawings, the tube of the exemplary type comprises a plurality of cathodes ll, hereinafter referred to as A cathodes, and a second plurality of cathodes I2, hereinafter designated as B cathodes,

all of the cathodes being mounted in a 'ci-rcular array with each A cathode II interposed two B cathodes 12. The main anode 13 may be and is shown to be ring-shaped, and is supported in spaced relation with the A and B cathodes. An auxiliary, start, reset or normalizing electrode M is also provided.

In one method of operating the stepping tube, the start electrode M is employed as a start'anode cooperating with the electrode 15 which serves as a start cathode. A suitable positive potential is applied to the main anode l3, a potential negative relative to the main anode potential is applied to the start cathode i5, and a potential pos-- itive with respect to the start cathode potential is applied to the start-anode M.

A discharge initially occurs between the start anode l4 and the start cathode 15, with conduction then transferring so as to'exist between the main anode,- l3 and the, start cathode. i5. If a negative pulse then be applied to the B cathode :2. the discharge will transfer initially so as to exist between the main anode and the first one of the B cathodes. This first B cathode is labeled IE in Fig. 2. At the cessation of the pulse, the discharge will transfer so as to exist between the main anode and the first one of the A cathodes in a counter-clockwise direction in the structure as shown in Fig. 2. This first A cathode i labeled i! in the structure as shown in Fig. 2 and is supplied with a suitable voltage through an impedance. In a similar manner, successive pulses applied to the B cathodes I2 will cause the conductive path in the tube to transfer so as to exist between the main anode I3 and the successive A cathodes II The directivity of the stepping is accomplished by the construction of the cathodes, in a manner fully set forth in the abovecited patent application or in any other suitable manner.

As the conductive path progresses step by step from position to position in the tube the conduction is limited to one path at a time, i. e., the conduction between the main anode and the previous A cathode II is extinguished. This may be accomplished by utilizing a suitable impedance in series with the main anode of the device whereby the increased voltage drop across this impedance, resulting from the transfer of conduction to a B cathode I2. is sufficient to cause the voltage between the main anode I3 and an A cathode I l to fall below the sustaining value.

One form of the invention is represented in Fig. 3 of the drawings. In this circuit, a multicathode pulse counting tube CT and a multicathode digit register tube RT are provided. These tubes may be of the type shown in Figs. 1 and 2, and in that event, in tube CT, main anode CMA is the correlative of anode I3 in Fig.

2, the first B cathode CBI is shown as cathode It in Fig. 2, the B cathodes CB2 to CBO are shown as the cathodes I2 in Fig. 2, the first A cathode CAI is shown as cathode I! in Fig. 2, A cathodes CA2 to CAO are the correlatives of cathodes II in Fig. 2. the start anode CSA is shown as electrode I 4 in Fig. 2 and the start cathode CS0 is shown as electrode I5 in Fig. 2. Fewer of the cathodes of tube RT are em loyed than is the case in tube CT, but with that difierence, the electrodes of tube RT are similarly designated to those of tube CT except for the appropriate change of the initial character in each designation.

As an exemplary embodiment of the invention, a portion of a mobile radio telephony system has been shown in Fig. 3. At each of the subscribers stations, such as the one shown in Fig. 3, a radio receiver RE and a radio transmitter TR are provided. This apparatus may be of any suitable type well known in the art, and is associated with the telephone handset HS in the normal manner. It is assumed that receiver RE is continuously operative to receive all of a relatively large group of subscribers telephonic designations, which are transmitted from one or more central points, and to apply all of these incoming designations to conductor 32 which is connected to battery through the upper winding of pulsing relay L. The receiver is further assumed to be operable in response to the receipt of any subscribers designation to connect ground to conductor 302 whereby this ground is extended through the No. 3 contact of the switchhook SW to operate offnormal relay ON.

Let it be assumed that a signal has been received by receiver RE and that receiver RE has operated to energize relay ON and to cause current to flow through the upper winding of relay L to operate relay L so that its armature is contacting the Nos. 3 and 4 contacts thereof. As the several series of pulses representing the sev eral letters or digits of the called partys designation are applied to conductor 3! through receiver RE, relay L will release at each pulse and reoperate at the termination of each pulse in the normal manner.

Additional windings are shown on relay L for special purposes. The lower winding of relay L is a biasing winding which opposes the upper or operating Winding sufficiently to force relay L to release when the operating winding is deenergized. When relay L operates, an energizing circuit for the lower winding of relay L is completed through resistor 304, No. 3 contact of relay L and through the No. 1 contact of relay ON to negative battery. When, subsequently, the upper winding of relay L is deenergized, the current in the lower winding of relay L is such as to assist the start of the release of relay L.

The middle winding of pulsing relay L functions as an aiding winding, assisting in both the operation and release of the relay. When relay L is operated, capacitor 305 is charged over a path from ground, middle winding of relay L, capacitor 305, No. 3 contact of relay L, No. 1 contact of relay ON and to negative battery. When relay L is released, the above-traced charging path is interrupted and capacitor 305 discharges through the winding of relay SR to ground. The current flow through the middle winding of relay L, as a result of the discharging of capacitor 305, is in a direction to aid the release of relay L and ensure the closure of the back contacts of that relay. When relay L is again operated, the charging path for capacitor 385 is reestablished and the current flowing through the middle winding of relay L as a result of the charging of that capacitor aids the operation of relay L thereby ensuring a steady front contact closure.

When relay OH is operated, positive battery is connected through the No. 3 contact of relay ON, conductor 386, through resistor 33? to the main anode CMA of the pulse counting tube CT and also through resistor 308 to the main anode RMA of the digit register tube RT. This potential on conductor 366 is also reduced by the voltagedivider action of resistors 31% and 3H and applied through capacitor 3I2 to the start anode CSA of tube CT; and the potential on conductor 306 is also reduced by the voltage-divider action of resistors (H3 and 314 and applied to the start anode RSA of the digit register tube RT. Since the start cathode CSC of tube CT is connected to negative battery through resistor 3I5, tube CT will undergo a control gap discharge between the start anode CSA and the start cathode CSC; and a transfer of discharge will immediately occur whereby the conductive path in tube CT will exist between the main anode CMA and the start cathode CSC'. A similar initial discharge and transfer of discharge will occur in tube RT since the start cathode RSC of that tube is connected to negative battery through resistor 3H2. Both of the tubes CT and RT are now prepared for stepping.

Upon the initial operation of relay L, a circuit is completed from negative battery, No. 1 contact of relay ON, No. 3 contact of operated relay L, winding of relay SR and to ground whereby relay SR. is operated. Relay SR is of the slow-torelease type so that it remains operated despite the several momentary interruptions of its energizing circuit resulting from the. pulsing of relay L. At the first release of relay L in response to the first pulse of the first digit of the received designation, negative battery is connected through the N0. 1 contacts of relays ON and L and to ground through resistor 320, and, in parallel therewith, to ground through capacitor 32I and the lower winding of the pulse generator transformer 322. The resultant positive pulse transmitted by transformer 322 will be ineffective to create any change in the circuits. At the-next operation of relay L at the end of the first pulse of the first digit of the received designation, capacitor 32I will discharge through resistor 32!! to ground whereby a negative pulse will'be tran mitted by the pulse generator transformer 322 through the front contact of operated relay SR, conductor 323 and to all of the B cathodes CBI to-CBEl of tube CT. In response to this first negative pulse applied to the B cathodes of tube CT, the conductive path in that tube Will be transferred so as to exist between the main anode CMA and the first B cathode CBI thereof. As a result, due to the increased Voltage drop across anode resistor 3531, the potential at the main anode CMA of tube CT will drop to a point where the potential difference between the main anode CMA and the start cathode CS0 is below the sustaining value, and that discharge path will thereby be extinguished. As the pulse attenuates, the discharge in tube CT will again transfer soas to exist between the main. anode CMA and the first A cathode CAI which is connected to negative battery through resistor 324. The rise in potential of cathode CAI due to the potential drop across resistor 324 appears at output terminal CI At the next momentary release and reoperation of relay L in response to the second pulse of the first digit of the received subscribers designation, the conductive path in tube CT is successively stepped to the next B cathode CB2 and then to the next A cathode CA2, with the prior conductive path between the main anode CMA and the A cathode CAI being extinguished. The rise in potential of cathode CA2 due to the potential drop across resistor 325 appears at output terminal C2.

As the subsequent first digit pulses are received, relay L will continue to follow the pulses alternately to charge and discharge capacitor 32! whereby transformer 322 will continue to transmit negative pulses to the B cathodes of tube CT. The stepping of tube CT continues in the abovedescribed manner, with the conductive path therein finally resting on that one of the A cathodes corresponding with the number of pulses received. Therefore, the output terminals C! to C0 associated with that A cathode will rise to a potential considerably positive relative to the negative- 50-volt potential which is applied to the output terminals which are connected to the non-conducting A cathodes.

At the termination of the pulses representing any one digit, relay RA is operated and remains operated during the inter-digital delay period. At any time that relay L is operated, capacitor 330 is charging over a path from positive battery, No. 3 contact of relay ON, conductor 3&6, windeing of relay RA, resistor 33E, capacitor 330 and to ground. As a consequence, a rising positive potential is applied to the start anode 334 of tube RAI'. However, the'time constant of that circuit is longer than the. time; between. the pulses .representing'any onev digit of asubscribers designation, and consequently prior to. the time; that a discharge is initiated in tube RAI, relay B will momentarily release and capacitor 330 will discharge, and, in fact, charge oppositely through resistor 335, No. 2 contact of released relay L, No. 1 contact of relay ON and to negative battery. At theend of the pulses representing any one digit, however, an interdigital time will elapse and during this longer period capacitor 330 will rise. to a sufficient positive potential to initiate a discharge in tube RAI between the start anode 334- and the cathode 335, which is connected to negativev battery. Since. the main anode of tube RAI is connected to positive battery through the winding of relay RA, tube RAI will undergo an immediate transfer of discharge whereby the conductive path will exist across the main gap of tube RAI and relay RA will be operated.

Upon the operation of relay RA, negative'bat tery is connected through the No. 1 contact of relay ON, No. 4 contact of operated relay L, conductor 338, No. 5 contact or operated relay RA and to the winding of relay RA, whereby relay RA is locked operated under the control of relay L. This negative battery potential at the No. 5 contact of relay RA is also applied via conductor 339 to the main anode of tube RAI whereby the conduction in tube RAI is extinguished.

Relay RA, in operating, connects selected ones of the output terminals CI to C0 of the pulse counting tube CT to the B cathodes of the digit register tube RT through individual capacitors 3M to 344 and individual transformers TI to T4. The exemplary showing of Fig. 3 assumes the use of the four-digit code 6814 as the designation of the subscribers station with which the apparatus is associated, but it will be apparent that the system may readily be modified in an obvious manner to accommodate codes comprising a greater or a fewer number of digits.

Since the digit register tube RT has been prepared for stepping as hereinbefore described, the conductive path in that tube may be stepped only by the application of a negative pulse to the first B cathode RBI. The application of negative pulses to any of the other B cathodes of tube RT will be ineffective at this time to modify the position ofthe conductive path in tube RT. The first B cathode RBI is connected to ground through the secondary winding of transformer TI 'and'the primary winding of transformer TI is connected through capacitor 3M, No. 1 contact of operated relay RA and via the exemplary cross-connection to output terminal C6 of the pulse counting tube CT. Therefore, if the first received digit is 6 so that terminal C5 is at a relatively high potential, upon the operation of relay RA, 9. pulse will be transmitted through capacitor MI and through the primary winding of transformer TI to ground whereby the secondary winding of transformer T! will apply a negative pulse to the first B cathode RBI of tube RT. This pulse is momentarily amplified by a momentary increase in the potential of terminal C6 in a manner hereinafter to be described. As a result, the conductive path in the digit register tube RT will be stepped so as to exist between the main anode RMA and the B cathode RBI; and, as that pulse attenuates, the conductive path in tube RT will again transfer so as to exist between the main anode RMA and the first A cathode RAI which is connected to negative battery through resistor 345. It will be apparent that had any other initial digit been recorded in the pulse counting tube CT, this stepping of the digit register tube RT would not have occurred.

Relay RA, in operating, also efiectively places a transient shunting path in parallel with resistor 39'! which is in series with the main anode CMA of tube CT. Thus, upon the operation of relay RA, a circuit is completed through conductor 341, which is connected to resistor 39? and to the main anode CMA of tube CT, No. 6 contact of operated relay RA, through the parallel resistance-capacitance timing network comprising resistor 348 and capacitor 349, through the primary winding of transformer T6, and to conductor 306 which is connected to resistor 30'! and to positive battery through the No. 3 contact of relay ON. Transiently, there will be a large current flow while capacitor 349 commences to charge over the above-traced path to the main anode CMA of tube CT, across the discharge path in tube CT to the A cathode CA6, resistor 350 and to negative battery. The potential at output terminal C6 will therefore rise due to the increased potential drop across resistor 35B, and this potential will be applied through the No. 1 contact of operated relay RA and through capacitor 3M to the primary winding of transformer Tl, in the manner hereinbefore described.

As the initial surge of charging current for capacitor 349 passes through the primary winding of transformer T5, a negative pulse is transmitted by the secondary winding of transformer T6, but this pulse is ineffective to create any change in the condition of the circuit. As the charging current for capacitor 349 passes its peak value and begins to decrease in value, the rate of change of current through the primary winding of transformer T5 will be opposite to that of the above-noted initial condition and therefore the secondary winding of transformer T6 will transmit a positive pulse to the start anode CSA of tube CT. As a result of the application of a positive pulse to the start anode CSA, a discharge is initiated between the start anode CSA and the start cathode CSC, an immediate transfer of discharge occurs whereby the conductive path in tube CT exists between the main anode CMA and the start cathode CSC, and the previously existing conducting path, which was assumed to exist between the main anode CMA and cathode CAB, is extinguished. This process whereby the tube is restored to its initial condition is referred to as normalization of the tube. It will be noted that the parameters of the charging circuit for capacitor 349 should be so selected that this normalization of the pulse counting tube CT will not occur prior to the transfer of the information stored in that tube to the digit register tube RT.

At the receipt of the first pulse of the secondreceived digit, relay L will release to release relay RA. Capacitor 349 will then discharge through resistor 348. At the termination of the first pulse of the second digit, relay L will reoperate and the pulse counting tube CT will be advanced one step in the manner hereinbefore described. Similarly, relay L will release and reoperate successively in response to the subsequent pulses representing the second digit and the conductive path in tube CT will be successively advanced accordingly. The circuits will continue to function in this fashion, with tube CT being stepped to a condition indicative of each received digit and then being normalized so that the conductive path in tube CT may then 8 be stepped to count the pulses representing the next digit.

If the successive digits correspond to the correlative digits in the subject subscribers designation, one pulse per digit will be transmitted to the digit register tube RT to advance the conductive path therein one step per digit. Therefore, if the preselected sequence of digits, i. e., 6814 is received, the conductive path in thedigit register tube RT will have been stepped so as to exist between the main anode RMA and the A cathode RA4. This A cathode is connected to negative battery through resistor 353 and. also through the winding of the signal relay S. Relay S will therefore be operated to energize a visual or audible signal such as lamp SI. It will be apparent that if any other series of digits is received or if the preselected digits are received in a different sequence, this subscriber will not be signaled.

If the subject subscriber is signaled, he lifts the handset HS and the No. 1 switchhook contact will be closed to connect the handset HS to the receiver RE. The No. 3 switchhook contact will be opened to release relay ON. On the other hand, if the incoming pulses do not designate the particular station shown in Fig. 3, relay ON will be released when the receiver RE removes the ground from conductor 3B2. In either case relay ON, in releasing, restores the apparatus to normal, extinguishing the discharged tubes, releasing the operated relays and deenergizing the signal means.

Another embodiment of the invention is shown in Figs. 4: and 5. The apparatus represented in these figures differs from that shown in Fig. 3 primarily in the use of relays as the registering means in place of the multicathode stepping tube RT which was employed in the first-discussed embodiment of the invention. With the exceptions hereinafter to be noted, the elements shown on Fig. l are substantially identical to and are interconnected in substantially the same way as are the corresponding elements in Fig. 3 and the operation of these circuits is identical to the operation of the corresponding circuits in Fig. 3. These elements in Fig. 4 are designated identically to the corresponding elements in the circuit of Fig. 3 except for a change of the initial element of the designation where appropriate.

The registering means shown in Fig. 5 comprises a plurality of steering relays AS to GS which are sequentially operated as the successive digits are received, and a plurality of register relays A, B, C, I, 2, 3 and d which are sequentially operated if the received digits correspond with the designation of the subscribers station with which the subject apparatus is associated.

Upon the operation of relay ON (Fig. 4) ground is connected through its No. 2 contact to conductor 455, through resistors 56! to 56?, through the windings of the register relays A, B, C, l, 2, 3 and t, respectively, and to negative battery. The resulting current flow is insufficient to operate the register relays, but serves to bias them so that they will operate more readily and also is sufiicient to maintain any of those relays operated once they have been operated.

The ground on conductor 455 is also extended through the No. 2 back contacts of the steering relays GS to BS in series, through the winding of relay AS and to battery whereby relay AS is operated. Relay AS, in operating, prepares an energizing circuit for the first register relay A by connecting the winding of relay A through the 9 No. 1 contact of relay AS; varistor V-i, conductor 5| l, to the No. 1 contact of relay RA. When relay RA operates during the first-interdigital" delay period, in the manner hereinbeforedescribed, conductor 5 is connected'to a preselected one of the output terminals CI to C of the pulse counting tube CT. Let it be assumed that the initial digit of the designation of the subscribers station with which the subject apparatusis-associated is 2 (or the letter A," B or 0 in standard telephonepractice). Therefore, an exemplary connection is shownbetween the output terminal C2 and conductor H through-the No. 1 contact of relay RA. If the first dig-it of the received designation is not 2, terminal (32 will be at negative battery potential and register relay A obviously will not be-operated. I-f, however, two pulses have been received whereby'the conductive path in tube-CT includes A cathode CA2 thereof, upon the operation of relayRA a surge 'of current occurs in the circuit comprising the main anode CMA and 'the cathode CA2 of tube CT, varistor VI and winding of -relay A whereby relay A is operated. This surge of cur rent results fromthe-placingof the network 'comprising capacitor 449, resistor 4'48 and the primary winding of transformer T6 in shunt of the main anode resistor'40'l in the manner hereinbefore described withrespect to a similar surge of current through "tube 'CT of Fig. 3. The-pa rameters of that surge-producing circuit should be selected to produce 'apulse of-a-predetermi-ned duration for a purpose'hereinafter -to-be noted.

At each operation of relay RA, the" next succeeding steering relay ES to GS 'is operated-to provide ;a successive association ofthe windings of the register relays B to 4 with the contacts of relay RA. Thus, ;at;the operation of relay R-A at the termination of 'the pulsesrepresenting the first 'received'digit, ground is connected through the No. 2 contact of relay ON, conductor-455, No. 10 contact of relay RA, conductor 460, No.2 contact andwinding of relay AS'and to battery whereby relay AS is locked operated. The ground on conductor '455-is also extended through'the No. 11 contact of relay RA toconductor 45-1, No. 3 contact of relayP2, which-is operated in amanner hereinafter to be described, conductor 48 2, No. 4 .contact'of operatedzrelay A'S, and through the winding of the second steering relay BS-to battery whereby relay BS-is operated. Relay BS locks operated through .its -No. 3 contact and through the No. 2 contacts of the succeeding steering relays CS to-GS to ground on conductor 455. Relay BS, in operating, interrupts, :at its No.2 contact, the energizing circuit for relay-AS. Relay BS, in operating, also conn'ectsthe winding of the secondregister relayB'through its No. 1 contact, varistor V2, conductor 5'l2,to the No. 2 contact'of relayRA. Since two successive digits may be the same in a subscriber's designation, it is-therefore essential that the surge of currentresulting from the shunting of the main ganode resistor 40'! cease before relay BS is operated. As an example, if the, registerrelays A to '4jare operable with 0.003 second after energizationand if the steering relays .AS to GS require 0.008 second to operate, thenLthe current surge maybe continued for'0.005'second, for example.

When relay RA releases at the receipt of the first pulse of .the second digit, ground is removed from conductors 460 and 462and relay AS will release. .At the end of the second 'digit,.relay RA will again operate, extending'the connection from the winding of relay'B to an output'terminal iei 10 of tube CT, such as, as an-exempl'aryconnection, to-output terminal 64 of tube CT. Assuming the second digit-of the subject subscribers designation to be the digit 4', if the second received digit is the digit 4, relay B will be operated. Since relay AS is-released, the ground on conductor 462 resultingfrom the reoperation of relay RA will be extended through the No. 5 contact of relay AS, No. 6 contact of relay BS and through the winding of relay GSto battery whereby relay CS is operated. Relay'CS locks operated through its No. 3 contact and through the No. 2 contacts of the succeeding steering relays DS to GS to groundon conductor 455. Relay CS also interrupts the above-traced locking path for relay BS but relay BS remains operated as long as relay RA remains operated due to the application of the ground on conductor 460 through the No. 3 contact of relay AS and-the No. 4 contact of relay BS-to the winding of relay BS.

As the succeeding digits arereceived, the steering relays AS to GS aresuccessively operated and the register relays A to 4 are operated if the successive received digitscorrespond with the designation of the station with which the subject apparatus is associated. In that event, the ground on conductor455 is extended through the front contacts of all of the register relays A to 4, through the winding of relay S and to ground. Relay S, in operating, lights the visual signal lamp VS and energizes the signal bell RS. When the subject called subscriber answers, relay ON releases to restore the circuits to normal. If the incoming pulses do notdesignate theparticular station shown in Figs. 4 and 5, when receiver RE removes the ground from conductor 4E2 relay ON will be released to restore the circuits to normal.

It willbenoted Mia/P11160316 cases, the delay between the operation of relays ON and Land the receipt-of :the first-pulse of the first digit may be of sufiicient duration to permit the discharge of tube RA! with a resultant operation of relay RA. Therefore, means are provided to prevent the second steering relay BS from being improperly operated in response to this operation of relay iRA. This means comprises gaseous discharge device-Pii and relay P2. The startelectrode 4510f tube P2! is connected to the output-terminal C2-ofthestepping tube CT. Fl'i-erefore at the first time that the conductive path in tube CT includes A cathode CA2, the potential at output terminal C2 will rise and this increased potential will beapplied to the start electro'cle4-5-i of tube P21. Since the oathode of tube P2 iisconnected-to negative battery through the No. 2 contact and-winding of relay P2, a discharge will-occur between the start electrode 451 and'the-cathode of tube 732i It is tobenoted that thisdischargein tube PM will occur even though the duration of the conductive path in tube-CT-between the main anode CMA and the cathodeC-AZ is only momentary, i. e., the'di'sch'argewill-occureven-though the initialdigit ofthereceiveddesignation is greater than 2'. In-theeventthat-the digit 1 is cm played asa first digit many of the-subscribers designations, it is obvious-that the start electrode 35i oftube P2! shouldbejconnected to output terminal CI' of the; stepping tubeilT.

Since the-main anode of tubePZi is connected to'pc-sitive' battery via conductor set and-the-No. 3 contact of-relay ON, the discharge in tube P2! will immediately --transfer so as 'to exist across the main gap of tube'PZI and relay-P2 will" be 11 operated. Relay P2 locks operated through its No. 1 contact and to ground via conductor 455. Relay P2, in operating, closes its No. 3 contact to permit the normal operation of the circuits as hereinbefore described.

It is to be understood that the above-described arrangements are but illustrative of the application of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. In a signalingsystem, a gaseous conduction device having an anode and a plurality of cathodes and responsive to electrical impulses applied thereto to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said cathodes, an impulse generator connected to said device and operable to transmit a series of groups of electrical impulses representing the elements of a code, counting means operable to count electrical indications applied thereto, apparatus operable at the termination of each of said groups of impulses for connecting only successive preselected ones of said cathodes to said counting means and to then restore said device to normal, said device being operative to transmit electrical indications to said counting means if the conductive path through device successively includes said successive preselected ones of said cathodes, and signal means operable by said counting means if said counting means has counted a number said electrical indications equal to the number of elements of said code.

2, In a signaling system, a gaseous conduction device having an anode, a first plurality of cathodes and a second plurality of cathodes and responsive to electrical impulses applied to said second plurality of cathodes to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator connected to said second plurality of cathodes of said device and operable to transmit a series of groups of electrical impulses representing the elements of a code, counting means operable to count electrical indications applied thereto, apparatus operable at the termination of each of said groups of impulses for connecting only successive preselected ones of said first plurality of cathodes to said counting means, means controlled by said apparatus to restore said device to normal, means for transmitting electrical indications to said counting means if the conductive path through said device successively includes said successive preselected ones of said first plurality of cathodes, and signal means operable by said counting means if said counting means has counted a number of said electrical indications equal to the number of elements of said code.

3. In a signaling system, a first gaseous conduction device having an anode and a plurality of cathodes and responsive to electrical impulses applied thereto to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said cathodes, an impulse generator connected to said first device and operable to transmit a series of groups of electrical impulses representing the elements of a code, a second gaseous conduction device having a plurality of distinct conduction positions and responsive to electrical indications applied thereto to advance the conductive path therein step by step from position to position, apparatus operable at the termination of each of said groups of impulses for connecting only successive preselected ones of the cathodes of said first device to said second device and to then restore said first device to normal, said first device being operative to transmit electrical indications to said second device if the conductive path through said first device successively includes said successive preselected ones of said cathodes of said first device, and signal means operable by said second device if said second device has counted a number of said electrical indications equal to the number of elements of said code.

4. In a signaling system, a first gaseous conduction device having an anode, a first plurality of cathodes and a second plurality of cathodes and responsive to electrical impulses applied to said second plurality of cathodes to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator connected to said second plurality of cathodes of said first device and operable to transmit a series of groups of electrical impulses representing the elements of a code, a second gaseous conduction device having a plurality of distinct conduction positions and responsive to electrical indications applied thereto to advance the conductive path therein step by step from position to position, apparatus operable at the termination of each of said groups of impulses for connecting successive preselected ones of said first plurality of cathodes of said first device to said second device, means controlled by said apparatus to restore said first device to normal, means for transmitting electrical indications to said second device if the conductive path through said first device successively includes said successive preselected ones of said first plurality of cathodes of said first device, and signal means operable by said second device if said second device has counted a number of said electrical indications equal to the number of elements of said code.

5. In a signaling system, a first gaseous conduction device having an anode, a first plurality of cathodes and a second plurality of cathodes and responsive to electrical impulses applied to said second plurality of cathodes to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, an impulse generator connected to said second pluralityof cathodes of said first device and operable to transmit a series of groups of electrical impulses representing the elements of a code, a second gaseous conduction device having an anode, a first plurality of cathodes corresponding in number to the number of elements in said code anda second plurality of cathodes and responsive to electrical indications applied to the said second plurality of cathodes thereof to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes thereof, apparatus operable at the termination of each of said groups of impulses for connecting successive preselected ones of said first plurality of cathodes of said first device to said second plurality of cathodes of said second device, means controlled by said apparatus to restore said first device to normal, means for transmitting electrical indications to the successive ones of said second plurality of cathodes of said second device if the conductive path through said first device successively includes said successive preselected ones of said first plurality of cathodes of said first device, and signal means connected to the last one of said first plurality of cathodes of said second device and operable if the conductive path in said second device has been advanced to include said last one of said first plurality of cathodes of said second device.

6. In a signaling system, a first gaseous conduction device having an anode, a start electrode, a first plurality of cathodes and a second plurality of cathodes and responsive to electrical impulses applied to said second plurality of cathodes to advance the conductive path there" through step by step so that said path exists between said anode and successive ones of said first plurality of cathodes, means for initially applying a discharge-initiating potential to said start electrode, an impulse generator connected to the second plurality of cathodes of said first device and operable to transmit a series of groups of electrical impulses representing the elements of a code, a second gaseous conduction device having an anode, a start electrode, a first plurality of cathodes corresponding in number to the number of elements in said code, and a second plurality of cathodes and responsive to electrical indications applied to the said second plurality of cathodes thereof to advance the conductive path therethrough step by step so that said path exists between said anode and successive ones of said first plurality of cathodes thereof, means for applying a discharge-initiating potential to the start electrode of said second device, apparatus operable at the termination of each of said groups of impulses for connecting successive preselected ones of said first plurality of cathodes of said first device to the successive ones of said second plurality of cathodes of said second device, means operable a timed interval after each operation of said apparatus to apply a discharge-initiating potential to the start electrode of said first device to restore said first device to normal, means comprising a capacitor and a transformer individual to each of said second plurality of cathodes of said second device for applying electrical indications to successive ones of said second plurality of cathodes of said second device if the conductive path through said first device successively includes said successive preselected ones of said first plurality of cathodes of said first device, and signal means connected to the last one of said first plurality of cathodes of said second device and operable if the conductive path in said second device has been advanced to include said last one of said first plurality of cathodes of said second device.

EDWARD VROOM.

tei'erences Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,662,877 Almquist Mar. 20, 1928 2,040,691 Hershey May 12, 1936 2,480,624 Barnard et a1 Aug. 30, 1949 

